University of Colorado biologist Dan Doak said in a study last year that the loss of whitebark pine and a decline in another food source, cutthroat trout, may have pushed bears into areas where they are more likely to be seen during aerial surveys.
He said that doesn’t necessarily mean there are more bears, only that more are being seen.
Doak and co-author Kerry Cutler also said wildlife officials mistakenly assumed female grizzly bears reproduce throughout a 30-year lifespan, compounding the government’s overly optimistic population estimates.
Doak said yesterday that he stood by his prior conclusions and hoped they would be further considered by the government study team as it sets up a monitoring program to keep track of bears after federal protections are lifted.
Van Manen said the study team’s aerial surveys are corroborated by other factors. That includes a doubling of the area occupied by grizzlies since the 1970s and a trapping program that consistently identifies new bears.
Yellowstone’s grizzly population is the second largest in the Lower 48, behind an estimated 1,000 bears in the Northern Continental Divide region that includes Glacier National Park. Smaller populations live in the Cabinet-Yaak, North Cascades and Selkirk areas of Idaho, Montana and Washington state.